1. Technical Field
The present invention relates to the printing and dyeing industry in the textile industry, and more particularly relates to a printing paste containing polysaccharide, sodium L-pyrrolidonecarboxylate and an etherified starch, a printing colorant containing the printing paste, and preparation methods of the printing paste and the printing colorant.
2. Related Art
In recent years, the principal component of a printing paste mainly contains, for example, starch, modified starch and sodium alginate. For example, the principal component of printing pastes disclosed in CN101314920A (Chinese Patent Application No. CN200810047683.0, publication date: Dec. 3, 2008, Composite printing paste for active dry and preparation method thereof), and CN1563558A (Chinese Patent Application No. 200410014343.X, publication date: Jan. 12, 2005, Composite denatured starch printing paste with adjustable viscosity, and preparation method and application thereof), is modified starch. The principal component of printing pastes disclosed in CN1600983A (Chinese Patent Application No. 03151285.2, publication date: Mar. 30, 2005, Printing paste and preparation method thereof), and CN1436891A (Chinese Patent Application No. 02110072.1, publication date: Aug. 20, 2003, Active dye printing paste and preparation method thereof), is formed by combining a carboxymethyl starch and sodium alginate. Although starch, dyes and printing and dyeing chemicals have good stability, the application of starch in printing is restricted due to poor rheological properties. However, when sodium alginate meets calcium ions or other metal ions in hard water, calcium alginate or alginates of other metals are generated and precipitated, and due to thus precipitates, carboxyl ions losses charges. Therefore, a secondary alcohol group=CHOH in sodium alginate paste may react with the dye, which not only damages the colorant performance, but also causes chromatic aberration due to unstable coloring, as well as influence the color fastness; moreover, sodium alginate is expensive, so the cost of the paste is high.
Consequently, people continue to develop printing pastes that do not use starch and sodium alginate as the principal component, for example, inorganic printing paste with montmorillonite powder or rectorite clay as the principal component (see CN1095120A (Chinese Patent Application No. 93105604.7, publication date: Nov. 16, 1994, Inorganic printing paste and production method), and CN1072976A (Chinese Patent Application No. 92101281.0, publication date: Jun. 9, 1993, Preparation and application of rectorite clay printing paste)); printing pastes with guar gum or xanthan gum as the main raw material (see CN1844558A (Chinese Patent Application No. 200610038915.7, publication date: Oct. 11, 2006, Guar gum silk printing paste and preparation method thereof), and CN1116670A (Chinese Patent Application No. 94110684.5, publication date: Feb. 14, 1996, Printing paste and production method thereof); and printing pastes with a galactomannan as the principal component (see CN1050419A (Chinese Patent Application No. 89107422.8, publication date: Apr. 3, 1991, Sesbania seed gum printing paste and preparation process thereof), and CN1922357A (Chinese Patent Application No. 200580005243.3, publication date: Feb. 28, 2007, Thickening agent for textile printing paste). However, theses paste are applicable in direct printing processes such as a rotary screen printing process and a flat screen printing process, but not applicable in cold transfer printing process.
In cold transfer printing, first a suitable printing colorant containing a paste and a dye is printing on a paper, to form a transfer printing paper with desired patterns or letters; next, a surface of the transfer printing paper with the dye is tightly combined with a fabric to be printed, and then the dyes is removed or peeled off from the paper by means of a pressure, and the patterns or letters on the transfer printing paper is transferred onto the fabric. CN1939946A (Chinese Patent Application No. 200610116181.X, publication date: Apr. 4, 2007, Production method of modified paste and printing colorant), discloses a cold transfer printing paste synthesized by polymerization of starch, vinyl acetate and acrylic acid, but the rheological property of the modified starch formed through graft copolymerization is poor, and the colorant prepared by the paste is sensitive to shear force, so that the viscosity of the colorant is lost when being continuously printed on a transfer paper surface at a high speed and during the transfer printing process, which influences the quality of printing.
Therefore, there is a need for a novel paste for cold transfer printing and printing colorant containing the paste that can overcome one or more disadvantages of the paste or colorants in the prior art.